1. Reporter ： Shao-Fung Chiu Advisor ： Cheng-Ho Chen Date ： 2015/12/22 1

2. 2 Outline Introduction Experimental Results and discussion Conclusions 2

3. 3 Outline Introduction Experimental Results and discussion Conclusions 3

4. Introduction 1. Stimuli-responsive polymeric membranes have attracted much research interest due to the abrupt property changes in response to small changes in external stimuli such as temperature, pH, solvent, chemical species, and photo-irradiation. 2. Comparing with other stimuli, pH sensitivity gives more choices both for the materials and applying environment as a novel and powerful technique. 4

5. 3. Polyethersulfone (PES) is a well-known polymeric material. The PES and PES based membranes show outstanding oxidative, thermal,and hydrolytic stability as well as good mechanical and film- forming properties. 4. Two random copolymers, P(AN-AA) and P(AN-MAA),were synthesized via free radical polymerization, the copolymers were directly blended with PES to prepare hollow fiber membranes by dry– wet spinning technique. 5

6. 6 Outline Introduction Experimental Results and discussion Conclusions 6

7. 7 Materials Acrylic acid Methyl acrylic acid Acrylonitrile N-methyl-2-pyrrollidone (NMP)

8. 8 Polyethersulfone (PES) Azo-bis-isobutyronitrile (AIBN)

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10. Experimental 10 Synthesis of P(AN-AA) AN and AA (ratio of 2:3) were dissolved in dioxane with the total monomer concentration of 30 wt.%. The initiator, Azo-bis-isobutryonitrile (AIBN) was introduced into the mixed solution with the weight ratio of 0.3% to the total monomers. And then the solution was stirred continuously until all reagents were completely dissolved. After passing nitrogen to the solution for 15 min, polymerization was carried out in airtight equipment at 60 °C for 24 h. The reaction was terminated by ethanol, and then washed several times with adding ethanol to remove the residual monomers and initiators thoroughly.

11. 11 The crude product was washed by hot de-ionized water until the pH value was neutral. The final copolymer P(AN-AA) was dried completely at 60 °C in a vacuum oven for 72 h. The synthesis of P(AN-MAA) was carried out in the same manner. Preparation : Synthesis of P(AN-MAA)

12. 12 Preparation of pH-sensitive PES hollow fiber membranes PES and the synthesized copolymers were dissolved in NMP in a glass reactor equipped with a mechanical stirrer to obtain clear homogeneous solutions, and the concentration of PES was 20 wt.%. The two synthesized copolymers were dissolved in NMP with a concentration of 5 wt.%,respectively. Five kinds of filters were prepared (HFM-20-0, HFM-AA-0.4, HFM-AA-0.8, HFM-MAA-0.45, and HFM-MAA-0.9) and the compositions of the hollow fibers are shown in Table 1. The polymer solutions were degassed and then used for the fabrication of pH-sensitive PES hollow fiber membranes by dry–wet spinning technique.

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14. 14 Outline Introduction Experimental Results and discussion Conclusions 14

15. FTIR spectra analysis of copolymers Results and discussion 15 Fig.1. FT-IR spectrums of copolymers: (a) P(AN-AA) and (b) P(AN-MAA)

16. SEM of the hollow fiber membrane 16 Fig.2. SEM images of the cross-sections of the PES hollow fiber membranes. (a) HFM-AA-0.4(0.4 wt.%); (b) HFM-AA-0.8(0.8 wt.%); (c) HFM-MAA-0.45(0.45 wt.%); (d) HFM-MAA-0.9,(0.9 wt.%);(e) HFM-20-0. Voltage: 20 kV; magnification:100×.

17. Membrane water flux as a function of pH value 17

18. 18 Outline Introduction Experimental Results and discussion Conclusions 18

19. Conclusions 19 1. Functional copolymers, P(AN-AA) and P(AN-MAA) were successfully synthesized via conventional free radical polymerization by FT-IR 2. The copolymers could be directly blended with PES to prepare hollow fiber membranes by dry–wet spinning technique. 3. Both of the two copolymer modified PES hollow fiber membranes showed evident pH sensitivity.

20. 20 Thank you for your attention